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Manohar A, Rossini L, Colvert G, Vigneault DM, Contijoch F, Chen MY, del Alamo JC, McVeigh ER. Regional dynamics of fractal dimension of the left ventricular endocardium from cine computed tomography images. J Med Imaging (Bellingham) 2019; 6:046002. [PMID: 31737745 PMCID: PMC6838603 DOI: 10.1117/1.jmi.6.4.046002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 10/14/2019] [Indexed: 11/14/2022] Open
Abstract
We present a method to leverage the high fidelity of computed tomography (CT) to quantify regional left ventricular function using topography variation of the endocardium as a surrogate measure of strain. 4DCT images of 10 normal and 10 abnormal subjects, acquired with standard clinical protocols, are used. The topography of the endocardium is characterized by its regional values of fractal dimension (F D ), computed using a box-counting algorithm developed in-house. The averageF D in each of the 16 American Heart Association segments is calculated for each subject as a function of time over the cardiac cycle. The normal subjects show a peak systolic percentage change inF D of 5.9 % ± 2 % in all free-wall segments, whereas the abnormal cohort experiences a change of 2 % ± 1.2 % ( p < 0.00001 ). Septal segments, being smooth, do not undergo large changes inF D . Additionally, a principal component analysis is performed on the temporal profiles ofF D to highlight the possibility for unsupervised classification of normal and abnormal function. The method developed is free from manual contouring and does not require any feature tracking or registration algorithms. TheF D values in the free-wall segments correlated well with radial strain and with endocardial regional shortening measurements.
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Affiliation(s)
- Ashish Manohar
- University of California San Diego, Department of Mechanical and Aerospace Engineering, La Jolla, California, United States
| | - Lorenzo Rossini
- University of California San Diego, Department of Mechanical and Aerospace Engineering, La Jolla, California, United States
| | - Gabrielle Colvert
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
| | - Davis M. Vigneault
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
| | - Francisco Contijoch
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
- University of California San Diego, Department of Radiology, La Jolla, California, United States
| | - Marcus Y. Chen
- National Heart, Lung, and Blood Institute, National Institutes of Health, Laboratory of Cardiac Energetics, Bethesda, Maryland, United States
| | - Juan C. del Alamo
- University of California San Diego, Department of Mechanical and Aerospace Engineering, La Jolla, California, United States
| | - Elliot R. McVeigh
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
- University of California San Diego, Department of Radiology, La Jolla, California, United States
- University of California San Diego, Cardiology Division, Department of Medicine, La Jolla, California, United States
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2
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Manohar A, Colvert GM, Schluchter A, Contijoch F, McVeigh ER. Anthropomorphic left ventricular mesh phantom: a framework to investigate the accuracy of SQUEEZ using Coherent Point Drift for the detection of regional wall motion abnormalities. J Med Imaging (Bellingham) 2019; 6:045001. [PMID: 31824981 PMCID: PMC6903427 DOI: 10.1117/1.jmi.6.4.045001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 11/18/2019] [Indexed: 11/14/2022] Open
Abstract
We present an anthropomorphically accurate left ventricular (LV) phantom derived from human computed tomography (CT) data to serve as the ground truth for the optimization and the spatial resolution quantification of a CT-derived regional strain metric (SQUEEZ) for the detection of regional wall motion abnormalities. Displacements were applied to the mesh points of a clinically derived end-diastolic LV mesh to create analytical end-systolic poses with physiologically accurate endocardial strains. Normal function and regional dysfunction of four sizes [1, 2/3, 1/2, and 1/3 American Heart Association (AHA) segments as core diameter], each exhibiting hypokinesia (70% reduction in strain) and subtle hypokinesia (40% reduction in strain), were simulated. Regional shortening (RS CT ) estimates were obtained by registering the end-diastolic mesh to each simulated end-systolic mesh condition using a nonrigid registration algorithm. Ground-truth models of normal function and of hypokinesia were used to identify the optimal parameters in the registration algorithm and to measure the accuracy of detecting regional dysfunction of varying sizes and severities. For normal LV function,RS CT values in all 16 AHA segments were accurate to within ± 5 % . For cases with regional dysfunction, the errors inRS CT around the dysfunctional region increased with decreasing size of dysfunctional tissue.
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Affiliation(s)
- Ashish Manohar
- University of California San Diego, Department of Mechanical and Aerospace Engineering, La Jolla, California, United States
| | - Gabrielle M. Colvert
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
| | - Andrew Schluchter
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
| | - Francisco Contijoch
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
- University of California San Diego, Department of Radiology, La Jolla, California, United States
| | - Elliot R. McVeigh
- University of California San Diego, Department of Bioengineering, La Jolla, California, United States
- University of California San Diego, Department of Radiology, La Jolla, California, United States
- University of California San Diego, Cardiology Division, Department of Medicine, La Jolla, California, United States
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3
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Augustin CM, Crozier A, Neic A, Prassl AJ, Karabelas E, Ferreira da Silva T, Fernandes JF, Campos F, Kuehne T, Plank G. Patient-specific modeling of left ventricular electromechanics as a driver for haemodynamic analysis. Europace 2017; 18:iv121-iv129. [PMID: 28011839 PMCID: PMC5386137 DOI: 10.1093/europace/euw369] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 08/26/2016] [Indexed: 01/30/2023] Open
Abstract
Aims Models of blood flow in the left ventricle (LV) and aorta are an important tool for analysing the interplay between LV deformation and flow patterns. Typically, image-based kinematic models describing endocardial motion are used as an input to blood flow simulations. While such models are suitable for analysing the hemodynamic status quo, they are limited in predicting the response to interventions that alter afterload conditions. Mechano-fluidic models using biophysically detailed electromechanical (EM) models have the potential to overcome this limitation, but are more costly to build and compute. We report our recent advancements in developing an automated workflow for the creation of such CFD ready kinematic models to serve as drivers of blood flow simulations. Methods and results EM models of the LV and aortic root were created for four pediatric patients treated for either aortic coarctation or aortic valve disease. Using MRI, ECG and invasive pressure recordings, anatomy as well as electrophysiological, mechanical and circulatory model components were personalized. Results The implemented modeling pipeline was highly automated and allowed model construction and execution of simulations of a patient’s heartbeat within 1 day. All models reproduced clinical data with acceptable accuracy. Conclusion Using the developed modeling workflow, the use of EM LV models as driver of fluid flow simulations is becoming feasible. While EM models are costly to construct, they constitute an important and nontrivial step towards fully coupled electro-mechano-fluidic (EMF) models and show promise as a tool for predicting the response to interventions which affect afterload conditions.
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Affiliation(s)
- Christoph M Augustin
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria.,Department of Mechanical Engineering, University of California, 5126 Etcheverry Hall, Berkeley, CA 94720, USA
| | - Andrew Crozier
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria
| | - Aurel Neic
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria
| | - Anton J Prassl
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria
| | - Elias Karabelas
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria
| | - Tiago Ferreira da Silva
- Department of Congenital Heart Disease/Pediatric Cardiology, German Heart Institute Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Joao F Fernandes
- Department of Congenital Heart Disease/Pediatric Cardiology, German Heart Institute Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Fernando Campos
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria.,Department of Congenital Heart Disease/Pediatric Cardiology, German Heart Institute Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Titus Kuehne
- Department of Congenital Heart Disease/Pediatric Cardiology, German Heart Institute Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Gernot Plank
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria
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4
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Affiliation(s)
- V.Y. Wang
- Auckland Bioengineering Institute and
| | - P.M.F. Nielsen
- Auckland Bioengineering Institute and
- Department of Engineering Science, Faculty of Engineering, University of Auckland, Auckland 1010, New Zealand; , ,
| | - M.P. Nash
- Auckland Bioengineering Institute and
- Department of Engineering Science, Faculty of Engineering, University of Auckland, Auckland 1010, New Zealand; , ,
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5
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Functional imaging of murine hearts using accelerated self-gated UTE cine MRI. Int J Cardiovasc Imaging 2014; 31:83-94. [DOI: 10.1007/s10554-014-0531-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/02/2014] [Indexed: 12/21/2022]
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Motaal AG, Coolen BF, Abdurrachim D, Castro RM, Prompers JJ, Florack LMJ, Nicolay K, Strijkers GJ. Accelerated high-frame-rate mouse heart cine-MRI using compressed sensing reconstruction. NMR IN BIOMEDICINE 2013; 26:451-457. [PMID: 23109290 DOI: 10.1002/nbm.2883] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 09/16/2012] [Accepted: 09/17/2012] [Indexed: 05/28/2023]
Abstract
We introduce a new protocol to obtain very high-frame-rate cinematographic (Cine) MRI movies of the beating mouse heart within a reasonable measurement time. The method is based on a self-gated accelerated fast low-angle shot (FLASH) acquisition and compressed sensing reconstruction. Key to our approach is that we exploit the stochastic nature of the retrospective triggering acquisition scheme to produce an undersampled and random k-t space filling that allows for compressed sensing reconstruction and acceleration. As a standard, a self-gated FLASH sequence with a total acquisition time of 10 min was used to produce single-slice Cine movies of seven mouse hearts with 90 frames per cardiac cycle. Two times (2×) and three times (3×) k-t space undersampled Cine movies were produced from 2.5- and 1.5-min data acquisitions, respectively. The accelerated 90-frame Cine movies of mouse hearts were successfully reconstructed with a compressed sensing algorithm. The movies had high image quality and the undersampling artifacts were effectively removed. Left ventricular functional parameters, i.e. end-systolic and end-diastolic lumen surface areas and early-to-late filling rate ratio as a parameter to evaluate diastolic function, derived from the standard and accelerated Cine movies, were nearly identical.
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Affiliation(s)
- Abdallah G Motaal
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands
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7
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Pourmorteza A, Schuleri KH, Herzka DA, Lardo AC, McVeigh ER. A new method for cardiac computed tomography regional function assessment: stretch quantifier for endocardial engraved zones (SQUEEZ). Circ Cardiovasc Imaging 2012; 5:243-50. [PMID: 22342945 DOI: 10.1161/circimaging.111.970061] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Quantitative assessment of regional myocardial function has important diagnostic implications in cardiac disease. Recent advances in CT imaging technology have allowed fine anatomic structures, such as endocardial trabeculae, to be resolved and potentially used as fiducial markers for tracking local wall deformations. We developed a method to detect and track such features on the endocardium to extract a metric that reflects local myocardial contraction. METHODS AND RESULTS First-pass CT images and contrast-enhanced cardiovascular magnetic resonance images were acquired in 8 infarcted and 3 healthy pigs. We tracked the left ventricle wall motion by segmenting the blood from myocardium and calculating trajectories of the endocardial features seen on the blood cast. The relative motions of these surface features were used to represent the local contraction of the endocardial surface with a metric we call stretch quantifier of endocardial engraved zones (SQUEEZ). The average SQUEEZ value and the rate of change in SQUEEZ were calculated for both infarcted and healthy myocardial regions. SQUEEZ showed a significant difference between infarct and remote regions (P<0.0001). No significant difference was observed between normal myocardium (noninfarcted hearts) and remote regions (P=0.8). CONCLUSIONS We present a new quantitative method for measuring regional cardiac function from high-resolution volumetric CT images, which can be acquired during angiography and myocardial perfusion scans. Quantified measures of regional cardiac mechanics in normal and abnormally contracting regions in infarcted hearts were shown to correspond well with noninfarcted and infarcted regions as detected by delayed enhancement cardiovascular magnetic resonance images.
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Affiliation(s)
- Amir Pourmorteza
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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8
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Price AN, Cheung KK, Cleary JO, Campbell AE, Riegler J, Lythgoe MF. Cardiovascular magnetic resonance imaging in experimental models. Open Cardiovasc Med J 2010; 4:278-92. [PMID: 21331311 PMCID: PMC3040459 DOI: 10.2174/1874192401004010278] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 09/27/2010] [Accepted: 10/04/2010] [Indexed: 12/19/2022] Open
Abstract
Cardiovascular magnetic resonance (CMR) imaging is the modality of choice for clinical studies of the heart and vasculature, offering detailed images of both structure and function with high temporal resolution. Small animals are increasingly used for genetic and translational research, in conjunction with models of common pathologies such as myocardial infarction. In all cases, effective methods for characterising a wide range of functional and anatomical parameters are crucial for robust studies. CMR is the gold-standard for the non-invasive examination of these models, although physiological differences, such as rapid heart rate, make this a greater challenge than conventional clinical imaging. However, with the help of specialised magnetic resonance (MR) systems, novel gating strategies and optimised pulse sequences, high-quality images can be obtained in these animals despite their small size. In this review, we provide an overview of the principal CMR techniques for small animals for example cine, angiography and perfusion imaging, which can provide measures such as ejection fraction, vessel anatomy and local blood flow, respectively. In combination with MR contrast agents, regional dysfunction in the heart can also be identified and assessed. We also discuss optimal methods for analysing CMR data, particularly the use of semi-automated tools for parameter measurement to reduce analysis time. Finally, we describe current and emerging methods for imaging the developing heart, aiding characterisation of congenital cardiovascular defects. Advanced small animal CMR now offers an unparalleled range of cardiovascular assessments. Employing these methods should allow new insights into the structural, functional and molecular basis of the cardiovascular system.
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Affiliation(s)
- Anthony N Price
- UCL Centre for Advanced Biomedical Imaging, Department of Medicine and UCL Institute of Child Health, University College London, UK
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9
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Niendorf T, Sodickson DK. Parallel imaging in cardiovascular MRI: methods and applications. NMR IN BIOMEDICINE 2006; 19:325-41. [PMID: 16705633 DOI: 10.1002/nbm.1051] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Cardiovascular MR imaging (CVMR) has become a valuable modality for the non-invasive detection and characterization of cardiovascular diseases. CVMR requires high imaging speed and efficiency, which is fundamentally limited in conventional cardiovascular MRI studies. With the introduction of parallel imaging, alternative means for increasing acquisition speed beyond these limits have become available. In parallel imaging some image data are acquired simultaneously, using RF detector coil sensitivities to encode simultaneous spatial information that complements the information gleaned from sequential application of magnetic field gradients. The resulting improvements in imaging speed can be used in various ways, including shortening long examinations, improving spatial resolution and/or anatomic coverage, improving temporal resolution, enhancing image quality, overcoming physiological constraints, detecting and correcting for physiologic motion, and streamlining work flow. Examples of each of these strategies will be provided in this review. First, basic principles and key concepts of parallel MR are described. Second, practical considerations such as coil array design, coil sensitivity calibrations, customized pulse sequences and tailored imaging parameters are outlined. Next, cardiovascular applications of parallel MR are reviewed, ranging from cardiac anatomical and functional assessment to myocardial perfusion and viability to MR angiography of the coronary arteries and the large vessels. Finally, current trends and future directions in parallel CVMR are considered.
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Affiliation(s)
- Thoralf Niendorf
- Department of Diagnostic Radiology, University Hospital, RWTH Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany
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10
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Abstract
Tagged cardiac magnetic resonance (MR) imaging can non-invasively image deformation of the left ventricular (LV) wall. Three-dimensional (3D) analysis of tag data requires fitting a deformation model to tag lines in the image data. In this paper, we present a 3D myocardial displacement and strain reconstruction method based on a B-spline deformation model defined in prolate spheroidal coordinates, which more closely matches the shape of the LV wall than existing Cartesian or cylindrical coordinate models. The prolate spheroidal B-spline (PSB) deformation model also enforces smoothness across and can compute strain at the apex. The PSB reconstruction algorithm was evaluated on a previously published data set to allow head-to-head comparison of the PSB model with existing LV deformation reconstruction methods. We conclude that the PSB method can accurately reconstruct deformation and strain in the LV wall from tagged MR images and has several advantages relative to existing techniques.
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Affiliation(s)
- Jin Li
- Electrical and Computer Engineering Department, 200 Broun Hall, Auburn University, AL 36849-5201, USA.
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11
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Aletras AH, Ingkanisorn WP, Mancini C, Arai AE. DENSE with SENSE. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 176:99-106. [PMID: 15946874 DOI: 10.1016/j.jmr.2005.05.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 05/03/2005] [Accepted: 05/04/2005] [Indexed: 05/02/2023]
Abstract
Displacement encoding with stimulated echoes (DENSE) with a low encoding strength phase-cycled meta-DENSE readout and a two fold SENSE acceleration (R = 2) is described. This combination reduces total breath-hold times for increased patient comfort during cardiac regional myocardial contractility studies. Images from phantoms, normal volunteers, and a patient are provided to demonstrate the SENSE-DENSE combination of methods. The overall breath-hold time is halved while preserving strain map quality.
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Affiliation(s)
- Anthony H Aletras
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA.
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12
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Ji S, Zhu Q, Dougherty L, Margulies SS. In vivo measurements of human brain displacement. STAPP CAR CRASH JOURNAL 2004; 48:227-37. [PMID: 17230268 DOI: 10.4271/2004-22-0010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Finite element models are increasingly important in understanding head injury mechanisms and designing new injury prevention equipment. Although boundary conditions strongly influence model responses, only limited quantitative data are available. While experimental studies revealed some motion between brain and skull, little data exists regarding the base of the skull. Using magnetic resonance images (MRI) of the caudal brain regions, we measured in vivo, quasi-static angular displacement of the cerebellum (CB) and brainstem (BS) relative to skull, and axial displacement of BS at the foramen magnum in supine human subjects (N=5). Images were obtained in flexion (7 degrees - 54 degrees ) and neutral postures using SPAMM tagging technique (N=47 pairs). Rigid body skull rotation angle from neutral posture (theta, degrees) was determined by extracting the edge feature points of the skull, and rotating and displacing the coordinates in one image until they matched those in the other. Tissue rotation was obtained by comparing tag lines in image pairs before and after flexion, and the motion of BS and CB were expressed relative to skull rotation and displacement. During flexion, the CB rotated in the flexion direction, exceeding the skull rotation, but relative BS rotations were negligible. Meanwhile, the BS moved caudally toward the foramen magnum. With a flexion angle of 54 degrees , the 95% confidence interval for the relative CB rotation was 2.7 degrees - 4.3 degrees , and 0.8 - 1.6mm for the relative BS axial displacement. Albeit quasi-static, this study provides important data that can be implemented to create more life-like boundary conditions in human finite element models.
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Affiliation(s)
- Songbai Ji
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
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13
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Bidaut L, Akhurst T, Downey RJ. Advanced imaging including PET/CT for cardiothoracic surgery. Semin Thorac Cardiovasc Surg 2004; 16:272-82. [DOI: 10.1053/j.semtcvs.2004.08.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Kim D, Gilson WD, Kramer CM, Epstein FH. Myocardial tissue tracking with two-dimensional cine displacement-encoded MR imaging: development and initial evaluation. Radiology 2004; 230:862-71. [PMID: 14739307 DOI: 10.1148/radiol.2303021213] [Citation(s) in RCA: 194] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A breath-hold two-dimensional cine magnetic resonance (MR) pulse sequence based on displacement encoding with stimulated echoes (DENSE) for quantitative myocardial motion tracking was developed and evaluated. In the sequence, complementary spatial modulation of magnetization was used for time-independent artifact suppression, and echo-planar imaging was used for rapid data sampling. Twelve healthy volunteers underwent cine DENSE MR imaging, and six of them also underwent conventional MR imaging myocardial tagging. The circumferential shortening component of strain (E(cc)) was measured on cine DENSE MR images and conventional tagged MR images. With complementary spatial modulation of magnetization, 10% or less of the total cine DENSE MR image energy was attributed to an artifact-generating echo during systolic imaging. Two-dimensional intramyocardial displacement and strain were measured at cine DENSE MR imaging with spatial resolution and temporal resolution of 2.7 x 2.7 mm and 60 msec, respectively. E(cc) measured at cine DENSE MR imaging correlated well with that measured at conventional MR imaging tagging (slope = 0.88, intercept = 0.00, R = 0.87).
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Affiliation(s)
- Daniel Kim
- Department of Radiology, University of Virginia Health System, Rm 1175, MR-4 Bldg, 409 Lane Rd, Charlottesville, VA 22908, USA
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15
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OZTURK CENGIZHAN, DERBYSHIRE JANDREW, MCVEIGH ELLIOTR. Estimating Motion From MRI Data. PROCEEDINGS OF THE IEEE. INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS 2003; 9:1627-1648. [PMID: 18958181 PMCID: PMC2574439 DOI: 10.1109/jproc.2003.817872] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
INVITED PAPER: Magnetic resonance imaging (MRI) is an ideal imaging modality to measure blood flow and tissue motion. It provides excellent contrast between soft tissues, and images can be acquired at positions and orientations freely defined by the user. From a temporal sequence of MR images, boundaries and edges of tissues can be tracked by image processing techniques. Additionally, MRI permits the source of the image signal to be manipulated. For example, temporary magnetic tags displaying a pattern of variable brightness may be placed in the object using MR saturation techniques, giving the user a known pattern to detect for motion tracking. The MRI signal is a modulated complex quantity, being derived from a rotating magnetic field in the form of an induced current. Well-defined patterns can also be introduced into the phase of the magnetization, and could be thought of as generalized tags. If the phase of each pixel is preserved during image reconstruction, relative phase shifts can be used to directly encode displacement, velocity and acceleration. New methods for modeling motion fields from MRI have now found application in cardiovascular and other soft tissue imaging. In this review, we shall describe the methods used for encoding, imaging, and modeling motion fields with MRI.
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Affiliation(s)
- CENGIZHAN OZTURK
- MEMBER, IEEE, The Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey, and also with the National Institutes of Health, National Heart, Lung, and Blood Institute (NHLBI), Bethesda, MD 20892-1538 USA (e-mail: )
| | - J. ANDREW DERBYSHIRE
- The National Institutes of Health, National Heart, Lung, and Blood Institute (NHLBI), Bethesda, MD 20892-1061 USA (e-mail: )
| | - ELLIOT R. MCVEIGH
- MEMBER, IEEE, The National Institutes of Health, National Heart, Lung, and Blood Institute, Bethesda, MD 20892-1061 USA and also with the Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA (e-mail: )
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16
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Rerkpattanapipat P, Mazur W, Link KM, Hundley WG. Assessment of cardiac function with MR imaging. Magn Reson Imaging Clin N Am 2003; 11:67-80. [PMID: 12797511 DOI: 10.1016/s1064-9689(02)00021-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A variety of black or white blood imaging techniques are available for assessing global and regional LV and RV function during cardiovascular MR imaging examinations. In addition to providing information about LV function at rest, these techniques provide diagnostic and prognostic information regarding myocardial ischemia and viability during MR imaging stress tests.
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Affiliation(s)
- Pairoj Rerkpattanapipat
- Cardiology Section, Wake Forest University School of Medicine, The Bowman Gray Campus, Winston-Salem, NC 27157-1045, USA
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17
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Peters DC, Ennis DB, McVeigh ER. High-resolution MRI of cardiac function with projection reconstruction and steady-state free precession. Magn Reson Med 2002; 48:82-8. [PMID: 12111934 PMCID: PMC2396263 DOI: 10.1002/mrm.10193] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The purpose of this study was to investigate the trabecular structure of the endocardial wall of the living human heart, and the effect of that structure on the measurement of myocardial function using MRI. High-resolution MR images (0.8 x 0.8 x 8 mm voxels) of cardiac function were obtained in five volunteers using a combination of undersampled projection reconstruction (PR) and steady-state free precession (SSFP) contrast in ECG-gated breath-held scans. These images provide movies of cardiac function with new levels of endocardial detail. The trabecular-papillary muscle complex, consisting of a mixture of blood and endocardial structures, is measured to constitute as much as 50% of the myocardial wall in some sectors. Myocardial wall strain measurements derived from tagged MR images show correlation between regions of trabeculae and papillary muscles and regions of high strain, leading to an overestimation of function in the lateral wall.
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Affiliation(s)
- Dana C Peters
- Laboratory of Cardiac Energetics, National Institutes of Health, Bethesda, Maryland 20892-1061, USA.
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18
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Papademetris X, Sinusas AJ, Dione DP, Constable RT, Duncan JS. Estimation of 3-D left ventricular deformation from medical images using biomechanical models. IEEE TRANSACTIONS ON MEDICAL IMAGING 2002; 21:786-800. [PMID: 12374316 DOI: 10.1109/tmi.2002.801163] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The quantitative estimation of regional cardiac deformation from three-dimensional (3-D) image sequences has important clinical implications for the assessment of viability in the heart wall. We present here a generic methodology for estimating soft tissue deformation which integrates image-derived information with biomechanical models, and apply it to the problem of cardiac deformation estimation. The method is image modality independent. The images are segmented interactively and then initial correspondence is established using a shape-tracking approach. A dense motion field is then estimated using a transversely isotropic, linear-elastic model, which accounts for the muscle fiber directions in the left ventricle. The dense motion field is in turn used to calculate the deformation of the heart wall in terms of strain in cardiac specific directions. The strains obtained using this approach in open-chest dogs before and after coronary occlusion, exhibit a high correlation with strains produced in the same animals using implanted markers. Further, they show good agreement with previously published results in the literature. This proposed method provides quantitative regional 3-D estimates of heart deformation.
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Mazur W, Brucks S, Darty SN, Rerkpattanapipat P. Magnetic resonance imaging in detection and functional assessment of coronary artery disease. Curr Atheroscler Rep 2002; 4:128-33. [PMID: 11822976 DOI: 10.1007/s11883-002-0036-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The past few years have brought significant improvements in the field of cardiovascular magnetic resonance imaging (MRI), which evolved from an experimental technique to a clinically accepted method of coronary artery disease detection (stress MRI) and viability assessment. In this article, we describe current MRI technology for detection and functional assessment of ischemia, such as dobutamine/atropine MRI, perfusion techniques, viability, and flow reserve in native coronary arteries and grafts. With further refinement in the technology, wide acceptance of cardiovascular MRI is anticipated in clinical practice.
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Affiliation(s)
- Wojciech Mazur
- Section on Cardiology, Wake Forest University School of Medicine (Bowman Gray Campus), Medical Center Boulevard, Winston-Salem, NC 27157-1045, USA.
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Kane AA, Butman JA, Mullick R, Skopec M, Choyke P. A new method for the study of velopharyngeal function using gated magnetic resonance imaging. Plast Reconstr Surg 2002; 109:472-81. [PMID: 11818823 DOI: 10.1097/00006534-200202000-00010] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The purpose of this project was to assess the feasibility of imaging the velopharynx of adult volunteers during repetitive speech, using gated magnetic resonance imaging (MRI). Although a number of investigators have used conventional MRI in the study of the human vocal tract, the mismatch between the lengthy time necessary to acquire sufficiently detailed images and the rapidity of movement of the vocal tract during speech has forced investigators to acquire images either while the subject is at rest or during sustained utterances. The technique used here acquired a portion of each image during repetitive utterances, building the full image over multiple utterance cycles. The velopharyngeal portal was imaged on a 1.5-Tesla GE Signa LX 8.2 platform with gated fast spoiled gradient echo protocol. An external 1-Hertz trigger was fed to the cardiac gate. Subjects synchronized utterance of consonant-vowel syllables to a flashing light synchronized with the external trigger. Each acquisition of 30 phases per second at a single-slice location took 22 to 29 seconds. Four consonant-vowel syllables (/pa/, /ma/, /sa/, and /ka/) were evaluated. Subjects vocalized throughout the acquisition, beginning 5 to 6 seconds beforehand to establish a regular rhythm. Imaging of the velopharyngeal portal was performed for sagittal, velopharyngeal axial (aligned perpendicular to the "knee" of the velum), axial, and coronal planes. Volumes were obtained by sequential acquisition of six to 10 slices (each with 30 phases) in the axial or sagittal planes during repetition of the /pa/ syllable. Spatiotemporal volumes of the single-slice data were sectioned to provide time-motion images (analogous to M-mode echocardiograms). Three-dimensional dynamic volume renderings of palate motion were displayed interactively (Vortex; CieMed, Singapore). A method suitable for the collection and visualization of four-dimensional information regarding monosyllabic speech using gated MRI was developed. These techniques were applied to a population of adult volunteer subjects with no history of speech problems and two patients with a history of cleft lip and palate. The techniques allowed good real-time visualization of velopharyngeal anatomy during its entire range of motion and was also able to image pathology-specific anatomic differences in the subjects with cleft lip and cleft palate. These methods may be applicable to a wide spectrum of problems in speech physiology research and for clinical decision-making regarding surgery for speech and outcomes analysis.
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Affiliation(s)
- Alex A Kane
- Imaging Sciences Training Program, Laboratory for Diagnostic Radiology Research, Diagnostic Radiology Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD, USA.
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Wyman BT, Hunter WC, Prinzen FW, Faris OP, McVeigh ER. Effects of single- and biventricular pacing on temporal and spatial dynamics of ventricular contraction. Am J Physiol Heart Circ Physiol 2002; 282:H372-9. [PMID: 11748084 DOI: 10.1152/ajpheart.2002.282.1.h372] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Resynchronization is frequently used for the treatment of heart failure, but the mechanism for improvement is not entirely clear. In the present study, the temporal synchrony and spatiotemporal distribution of left ventricular (LV) contraction was investigated in eight dogs during right atrial (RA), right ventricular apex (RVa), and biventricular (BiV) pacing using tagged magnetic resonance imaging. Mechanical activation (MA; the onset of circumferential shortening) was calculated from the images throughout the left ventricle for each pacing protocol. MA width (time for 20-90% of the left ventricle to contract) was significantly shorter during RA (43.6 +/- 17.1 ms) than BiV and RVa pacing (67.4 +/- 15.2 and 77.6 +/- 16.4 ms, respectively). The activation delay vector (net delay in MA from one side of the left ventricle to the other) was significantly shorter during RA (18.9 +/- 8.1 ms) and BiV (34.2 +/- 18.3 ms) than during RVa (73.8 +/- 16.3 ms) pacing. Rate of LV pressure increase was significantly lower during RVa than RA pacing (1,070 +/- 370 vs. 1,560 +/- 300 mmHg/s) with intermediate values for BiV pacing (1,310 +/- 220 mmHg/s). BiV pacing has a greater impact on correcting the spatial distribution of LV contraction than on improving the temporal synchronization of contraction. Spatiotemporal distribution of contraction may be an important determinant of ventricular function.
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Affiliation(s)
- Bradley T Wyman
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Osman NF, Sampath S, Atalar E, Prince JL. Imaging longitudinal cardiac strain on short-axis images using strain-encoded MRI. Magn Reson Med 2001; 46:324-34. [PMID: 11477637 DOI: 10.1002/mrm.1195] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This article presents a new method for measuring longitudinal strain in a short-axis section of the heart using harmonic phase magnetic resonance imaging (HARP-MRI). The heart is tagged using 1-1 SPAMM at end-diastole with tag surfaces parallel to a short-axis imaging plane. Two or more images are acquired such that the images have different phase encodings in a direction orthogonal to the image plane. A dense map of the longitudinal strain can be computed from these images using a simple, fast computation. Simulations are conducted to study the effect of noise and the choice of out-of-plane phase encoding values. Longitudinal strains acquired from a normal human male are shown.
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Affiliation(s)
- N F Osman
- Department of Radiology, The Johns Hopkins University, Baltimore, Maryland 21287-0845, USA.
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Abstract
Important advances in rapid magnetic resonance (MR) imaging technology and its application to cardiovascular imaging have been made during the past decade. High-field-strength clinical magnets, high-performance gradient hardware, and ultrafast pulse sequence technology are rapidly making the vision of a comprehensive "one-stop shop" cardiac MR imaging examination a reality. This examination is poised to have a significant effect on the management of coronary artery disease by means of assessment of wall motion with tagging and pharmacologic stress testing, evaluation of the coronary microvasculature with perfusion imaging, and direct visualization of the coronary arteries with MR coronary angiography. This article reviews current state-of-the-art pulse sequence technology and its application to the evaluation of ischemic heart disease by means of MR tagging with dobutamine stress testing, MR perfusion imaging, and MR coronary angiography. Cutting edge areas of research in coil design and exciting new areas of metabolic and oxygen level-dependent imaging are also explored.
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Affiliation(s)
- S B Reeder
- Department of Radiology, Rm H1306, Stanford University, 300 Pasteur Dr, Stanford, CA 94304, USA.
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Peters DC, Epstein FH, McVeigh ER. Myocardial wall tagging with undersampled projection reconstruction. Magn Reson Med 2001; 45:562-7. [PMID: 11283982 PMCID: PMC2396261 DOI: 10.1002/mrm.1076] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Azimuthally undersampled projection reconstruction (PR) acquisition is investigated for use in myocardial wall tagging with MR using grid tags to provide increased temporal and spatial resolution. PR can provide the high-resolution images required for tagging with very few projections, at the expense of artifact. Insight is provided into the PR undersampling artifact, in the context of measuring myocardial motion with tags. For Fourier transform imaging, at least 112 phase-encodings must be collected to image tagging grids spaced 7 pixels apart. PR requires about 80 projections, a 1.4-fold reduction in scan time. Magn Reson Med 45:562-567, 2001. Published 2001 Wiley-Liss, Inc.
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Affiliation(s)
- D C Peters
- Laboratory of Cardiac Energetics, National Institutes of Health, Bethesda, Maryland 20892-1061, USA.
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Reeder SB, Faranesh AZ. Ultrafast pulse sequence techniques for cardiac magnetic resonance imaging. Top Magn Reson Imaging 2000; 11:312-30. [PMID: 11153700 DOI: 10.1097/00002142-200012000-00002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
Cardiac magnetic resonance imaging is a rapidly emerging field that has seen tremendous advances in the past decade. Central to the development of effective imaging strategies has been the advent of high-performance gradient hardware and the exploitation of their speed characteristics through specialized pulse sequences well suited for cardiac imaging. These advances have facilitated unprecedented acquisition times that now approach echocardiographic frame rates, while maintaining excellent image quality. This article provides a detailed overview of advanced pulse sequence technology and approaches currently taken to maximize speed performance and image quality. In particular, segmented K-space techniques that include single-echo and multiecho spoiled gradient-echo imaging as well as steady-state free precession imaging are discussed. Finally, spiral and fast spin-echo techniques are explored. Examples of common applications of these pulse sequences are presented.
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Affiliation(s)
- S B Reeder
- Department of Radiology, Stanford University, California, USA
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Rerkpattanapipat P, Link KM, Hamilton CA, Hundley WG. Clinical utility of assessments of left ventricular systolic function and coronary arterial blood flow during pharmacological stress with magnetic resonance imaging. Top Magn Reson Imaging 2000; 11:399-405. [PMID: 11153706 DOI: 10.1097/00002142-200012000-00008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- P Rerkpattanapipat
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1045, USA
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Declerck J, Denney TS, Oztürk C, O'Dell W, McVeigh ER. Left ventricular motion reconstruction from planar tagged MR images: a comparison. Phys Med Biol 2000; 45:1611-32. [PMID: 10870714 PMCID: PMC2396312 DOI: 10.1088/0031-9155/45/6/315] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Through recent development of MR techniques, it is now possible to assess regional myocardial wall function in a non-invasive way. Using MR tagging, space is marked with planes which deform with the tissue, providing markers for tracking the local motion of the myocardium. Numerous methods to reconstruct the three-dimensional displacement field have been developed. The aim of this article is to provide a framework to quantitatively compare the performance of four methods the authors have developed. Five sets of experiments are described, and their results are reported. Instructions are also provided to perform similar tests on any method using the same data. The experiments show that some characteristic properties of the methods, such as sensitivity to noise or spatial resolution, can be quantitatively classified. Cross-comparison of performances show what range values for these properties can be considered acceptable.
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Affiliation(s)
- J Declerck
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.
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Ozturk C, McVeigh ER. Four-dimensional B-spline based motion analysis of tagged MR images: introduction and in vivo validation. Phys Med Biol 2000; 45:1683-702. [PMID: 10870718 PMCID: PMC2041909 DOI: 10.1088/0031-9155/45/6/319] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In MRI tagging, magnetic tags-spatially encoded magnetic saturation planes-are created within tissues acting as temporary markers. Their deformation pattern provides useful qualitative and quantitative information about the functional properties of underlying tissue and allows non-invasive analysis of mechanical function. The measured displacement at a given tag point contains only unidirectional information; in order to track the full 3D motion, these data have to be combined with information from other orthogonal tag sets over all time frames. Here, we provide a method to describe the motion of the heart using a four-dimensional tensor product of B-splines. In vivo validation of this tracking algorithm is performed using different tagging sets on the same heart. Using the validation results, the appropriate control point density was determined for normal cardiac motion tracking. Since our motion fields are parametric and based on an image plane based Cartesian coordinate system, trajectories or other derived values (velocity, acceleration, strains ...) can be calculated for any desired point within the volume spanned by the control points. This method does not rely on specific chamber geometry, so the motion of any tagged structure can be tracked. Examples of displacement and strain analysis for both ventricles are also presented.
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Affiliation(s)
- C Ozturk
- Medical Imaging Laboratory, Johns Hopkins University, Baltimore, MD 21205, USA.
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Curry CW, Nelson GS, Wyman BT, Declerck J, Talbot M, Berger RD, McVeigh ER, Kass DA. Mechanical dyssynchrony in dilated cardiomyopathy with intraventricular conduction delay as depicted by 3D tagged magnetic resonance imaging. Circulation 2000; 101:E2. [PMID: 10618315 DOI: 10.1161/01.cir.101.1.e2] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- C W Curry
- Division of Cardiology, the Department of Medicine, the Department of Biomedical Engineering, and the Department of Radiology The Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA
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Abstract
This article introduces a new image processing technique for rapid analysis of tagged cardiac magnetic resonance image sequences. The method uses isolated spectral peaks in SPAMM-tagged magnetic resonance images, which contain information about cardiac motion. The inverse Fourier transform of a spectral peak is a complex image whose calculated angle is called a harmonic phase (HARP) image. It is shown how two HARP image sequences can be used to automatically and accurately track material points through time. A rapid, semiautomated procedure to calculate circumferential and radial Lagrangian strain from tracked points is described. This new computational approach permits rapid analysis and visualization of myocardial strain within 5-10 min after the scan is complete. Its performance is demonstrated on MR image sequences reflecting both normal and abnormal cardiac motion. Results from the new method are shown to compare very well with a previously validated tracking algorithm. Magn Reson Med 42:1048-1060, 1999.
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Affiliation(s)
- N F Osman
- Department of Electrical and Computer Engineering, Center for Imaging Science, The Johns Hopkins University, Baltimore, MD 21218, USA
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Abstract
MRI myocardial tagging is now a well-developed method for evaluation of regional myocardial contraction. A series of progressively more refined imaging strategies, combined with advances in analytic strategies have provided a strong armamentarium of methods. Important insights into normal human physiology of left ventricular systolic and diastolic function have been developed using one-dimensional, two-dimensional and three-dimensional analyses of myocardial deformation. In disease states, improved understanding and detection of early alterations in myocardial function in hypertensive heart disease has been possible. In addition, improved understanding of effects of ischemia and infarction on regional function has been possible. Further, after acute myocardial infarction, clearer definition of the natural history of contractile dysfunction in the infarct region and the zone adjacent to the infarct have been possible. Similarly, effects on regional function of a number of important pharmacologic agents used for treatment, such as angiotensin converting enzyme inhibitors, beta blockers and angiotensin receptor blockers have been characterized. In the cardiomyopathies, myocardial tagging has permitted more reliable assessment of heterogeneity of segmental function, especially in hypertrophic cardiomyopathy. Finally, initial applications of myocardial tagging to assessment of right ventricular regional function in hypertrophied hearts with and without major congenital abnormalities have generated advances in understanding of effects of hypertrophy on right ventricular function.J. Magn. Reson. Imaging 1999;10:609-616.
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Affiliation(s)
- N Reichek
- Division of Cardiology, Allegheny General Hospital, and Department of Medicine, MCP-Hahnemann School of Medicine, Pittsburgh, Pennsylvania 15212, USA.
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Aletras AH, Balaban RS, Wen H. High-resolution strain analysis of the human heart with fast-DENSE. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 1999; 140:41-57. [PMID: 10479548 DOI: 10.1006/jmre.1999.1821] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Single breath-hold displacement data from the human heart were acquired with fast-DENSE (fast displacement encoding with stimulated echoes) during systolic contraction at 2.5 x 2.5 mm in-plane resolution. Encoding strengths of 0.86-1.60 mm/pi were utilized in order to extend the dynamic range of the phase measurements and minimize effects of physiologic and instrument noise. The noise level in strain measurements for both contraction and dilation corresponded to a strain value of 2.8%. In the human heart, strain analysis has sufficient resolution to reveal transmural variation across the left ventricular wall. Data processing required minimal user intervention and provided a rapid quantitative feedback. The intrinsic temporal integration of fast-DENSE achieves high accuracy at the expense of temporal resolution.
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Affiliation(s)
- A H Aletras
- Laboratory of Cardiac Energetics, NHLBI, Bethesda, Maryland 20892, USA
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